Database.Explain 1NF, give example

📘 First Normal Form (1NF)

1NF (First Normal Form) is the basic level of normalization.
A table is in 1NF if:

1. All columns contain atomic (indivisible) values
2. Each row is unique
3. Each column contains values of a single type
4. There are no repeating groups or arrays

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❌ Example: Not in 1NF

Table: Students

StudentID	Name	Subjects
1	Alice	Math, Physics
2	Bob	Chemistry

• ❌ The Subjects column has multiple values in one field → not atomic
• This is not in 1NF

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✅ Example: In 1NF

To convert to 1NF, we split multivalued fields into separate rows:

Table: StudentSubjects

StudentID	Name	Subject
1	Alice	Math
1	Alice	Physics
2	Bob	Chemistry

• ✅ Now each field is atomic
• ✅ No repeating groups
• ✅ 1NF is satisfied

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🧠 Tip to Remember:

“No lists or arrays in cells, just one value per column per row.”